Biol 441 exam 2 Flashcards Preview

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Flashcards in Biol 441 exam 2 Deck (21):
1

Curie's principle

Effects have the same symmetry as their causes (and sometimes more)

2

Fucus brown alga symmetry breaking

Roots sprout on the darker side of the cell at the spherical 1 cell stage

3

Frog/salamander symmetry breaking

Point of sperm entry determines anterior-posterior (or dorsal-ventral) axis

4

Notochord is replaced by (in mammals and birds)

vertebral column

5

Notochord geometry

Stacked, inflated coins with large vacuoles

6

Notochord movement capabilities

Bending side to side
No anterior-posterior compression

7

Notochord convergent extension

Notochord cells extend processes sideways
They attach to each other and contract, stretching itself out

8

Notochord cells in reptiles, birds, and mammals

Last to leave the surface of the embryo, the epiblast, at Hensen's Node

9

Somite formation location

Beside the neural tube at the paraxial mesoderm

10

Theories of somite splitting (2)

Active constriction
Decrease of cell-cell adhesion

11

Progenitor somites

Somitomeres

12

Theories of somite signalling (2)

Genetic mechanism similar to fly segmentation (Hox genes)
"Clock and wavefront" hypothesis

13

Somite subdivisions (4)

Dermatome
Myotome
Anterior sclerotome
Posterior sclerotome

14

Lateral plate mesoderm layer divisions (2)

Splanchnic layer
Somatic layer

15

Space in-between 2 layers of LPM
special feature in reptiles, birds, and mammals

Coelomic cavity
filled with coelomic fluid
in reptiles, birds, and mammals, is continuous with the space in-between the chorion and amnion, called the extraembryonic coelom

16

Heart development location

Where the 2 sides of the LPM meet

17

Heart development if barrier blocks joining of LPM

2 normally functioning hearts

18

PGC origin in birds

Crescent shaped area of extra-embryonic tissue in front of head

19

PGC origin in flies and nematodes

The rearmost part of the embryo
Determined by special pre-positioned granules

20

PGC origin in mammals and amphibials

Extreme ventral endoderm

21

Possible mechanisms of PGCs migrating to gonads

Selective adhesion
Temporal chemotaxis
Spatial chemotaxis